This is a nice recipe for a party as it can be made well ahead of time. It is a common dish in Peru, which of course is the birthplace of the domesticated potato.
3 lbs potatoes. I use Yukon Gold or a Papa Amarilla in Peru.
1 Tablespoon of paprika or 4 Tablespoons of aji Amarillo paste if you have it.
1 lb poached fish fillets (see below)
1 cup peas (fresh [poached] or canned)
1 cup diced carrots poached.
4 ounces butter
7 oz (210 g) canned (evaporated) milk
½ cup plus 2 Tbs mayonnaise
12 olives cut in half (traditionally these should be purple Peruvian olives, but any variety will do)
Salt to taste
You can use almost any variety of fish, including canned tuna. I use either salmon or lenguado, depending on where I am.
Prepare a broth with 2 cups water, one cup white wine, 6 cloves of garlic (cut in half), 1 tablespoon thyme or marjoram (or almost any other herb).
Simmer these ingredients for at least 15 minutes.
Strain out solids, saving the broth.
Place fish fillets in a single layer in the bottom of a frying pan.
Pour strained broth over the fillets until just covered.
Poach gently for about 10 minutes, until the fish is just done. Remove from the heat and let sit in broth for a few minutes.
Fixing the causa.
You will need a deep 9 X 12 baking dish. Glass is best, but not required.
Peel the potatoes and cut into 1-2 inch cubes.
Bring 2 qts (more or less) of salted water to a boil and add the potatoes. Cook until just done, about 10 minutes.
Strain the potatoes and return to a large mixing bowl. Add butter, canned milk, paprika (or aji amarillo) and salt to taste. Mash the potatoes until there are no lumpy pieces. Set aside to cool.
Remove the skin from the fish fillets and shred the fish. Add ½ cup mayonnaise and mix well.
Spread the fish mixture evenly in the bottom of the baking dish (there is no need to oil the pan)
Put a layer of mashed potatoes on top of the fish. I do this by making a series of potato patties and laying them gently over the fish, filling in the holes with bits and pieces.
Mix the cooked peas and carrots together and spread them on top of the layer of potato.
Lay down the last layer of mashed potatoes, again filling in all the holes and covering exposed peas and carrots.
Score the surface into 24 squares, then, using a thin sharp knife, cut the causa into the 24 pieces (don’t remove it from the baking dish!)
In the middle of each square, put a half-teaspoon of mayonnaise and then an olive half.
Chill the causa for at least an hour until well set.
Use a spatula to serve the individual squares. You will mess up the first one, so keep that for yourself.